Conventionally, as described in Japanese Laid-Open Patent Publication No. 2003-18794, for example, this type of motor is configured by a motor portion having a rotor received in a yoke housing and a speed reducing portion mounted at an output-side end portion of the motor portion to reduce the rotating speed of the motor portion. In the motor portion, the rotary shaft of the rotor projects from an opening of the yoke housing at the axial output side toward the speed reducing portion. A brush holder for holding a feeder brush is arranged in the opening of the yoke housing to supply electric power to a commutator. The speed reducing portion includes a gear housing, which is fixed to an output-side end portion of the yoke housing through a fastening member such as a screw. The gear housing accommodates members for configuring a speed reducing mechanism, including a worm gear and a worm wheel. Drive force produced by the motor portion is output in a state in which the rotating speed is reduced by the speed reducing mechanism.
The motor includes a positioning projection, which projects axially in the gear housing. A positioning hole, with which the positioning projection is engaged, is formed in an inner surface of the brush holder. To join the motor portion and the speed reducing portion together, the positioning projection of the gear housing is engaged with the positioning hole of the brush holder. The motor portion and the speed reducing portion are thus positioned in a direction perpendicular to the axial directions of the motor portion, which includes the brush holder, and the gear housing. This facilitates joint of the motor portion and the speed reducing portion.
The brush holder includes an urging member for pressing the brush against the commutator, a noise suppression element such as a capacitor, and a terminal member for electrical connection of a noise suppression element and the brush. These components are arranged at a high density to reduce the size of the brush holder in a direction perpendicular to the axial direction. If the brush holder includes positioning portions as described above, the brush holder is enlarged in the direction perpendicular to the axial direction to have space for mounting the positioning portions. In this regard, more improvement is necessary.